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PHYSICS 12 Prof: Kim Griest Formula sheet Energy = Work = Force × Distance, (E = F d). Potential Energy: P.E. = mgh. 2 For gravity, g = 9.8m/sec , (F = weight = mg). 1 Kinetic Energy: K.E. = 2 mv 2 Power = Energy/Time, (P = E/t, or E = P t), and also P = F v. Heat energy: ∆E = cP m∆T . 2 Wind Power: P/A2 = 6.1 × 10−4 v 3 (kW/m ), v in units of m/sec, Area, A, in m2 ; theoretical maximum efficiency is 59%. Carnot Efficiency = (Thot − Tcold )/Thot ; T in 0 K. 0 C = 95 (0 F − 32), 0 K =0 C + 273. Coefficient of Performance (COP) = Thot /(Thot − Tcold ) = Qhot /(Qhot − Qcold ); T in 0 K. Energy Efficiency Ratio (EER) = Tcold /(Thot − Tcold ) = Qcold /(Qhot − Qcold ) = Qcold /W ; T in 0 K. Drag force Fad = CD Af v 2 /370; v in miles/hr, Af in ft2 , Fad in pounds. Rolling force Fr = Cr mv, v in miles/hr. Acceleraton force Facc = ma. Hill climbing force Fh = msg. Exponential growth N = N0 (1 + r)n Energy loss: Q(Btu) = 24A(degree days)/RT , Q 0 2 t (Btu/hr) = A(Ti − To )/R; T in F, A in ft . 0 Degree-days = (65 F − Tout )(number of days) Adiabatic Lapse Rate (ALR) = 3 0 F per 1000 ft Price of fuels 42 Gallon barrel of oil: $130.00 1000 cubic feet of natural gas: $13.00 1 kilowatt hour of electricity: $0.12 1 gallon gasoline: $4.00 1 gram of Uranium: $0.10 Heat capacities in Btu/( ft3 0 F) Water: 62 Wood: 29 Stone: 20 Concrete: 22 Facts and Factors 1 gallon of water weighs 8.3 pounds. density of water is 1gm/cm3 . 1 Watt = 1 Joule/sec = 3.41 Btu/hr = 1.34 × 10−3 horsepower = 0.737 ft lb/sec. 1 Calorie = 1 kilocalorie = 1000 calories. 1 mile = 1609 meters = 5280 ft. 1ton = 2000lb = 0.907 metric tonne. mass of proton and neutron about 1.67 ×10−27 kg. Methane is CH4 , Carbon Dioxide is CO2 speed of light = 3 × 108 meters/sec 1 ft = 0.3048 meter 1 kg = 2.2 lbs 2006 population of the U.S. is about 300 million R-values: inside air layer:0.68, outside air layer:0.17, glass:0.03, plywood:0.94 1